I’ve spent a good part of my career pointing out flaws in mainstream media, including the possibility that fewer reporters would lead to lower quality and erode trust. “The press” has made many mistakes that have alienated readers.

But that is not mostly what explains the recent drop in public trust in the press.

Let’s look at the numbers. We have indeed seen a dramatic drop in public trust for the “mass media” – from 55% who trusted the press in 1999 down to 32% in 2016. And there’s been a particularly large drop recently, from 40% in 2015 to 32% this year.

But here’s the key: it was driven almost entirely by a drop in confidence from Republicans. GOP trust in the mass media dropped from 32% in 2015 to 14% in 2016.

Gee, why would the press suddenly be viewed as half as trustworthy in just one year? Did the press get twice as bad?

Isn’t it possible that Trump supporters were actually moved by their candidate saying, “the media is pathetic;” “much of the media is totally dishonest;” “They’re Scum. They’re Horrible People. They Are So Illegitimate”; “very dishonest and totally biased media“; and “disgusting and corrupt.”

As with so many Trump innovations, he built on an approach the Republicans have taken for a few decades. Looking at the same chart, we can see that a good chunk of the declining trust in the press over the past few decades was fueled by Republicans. That number dropped from 52 percent down to 14 percent in less than 20 years. It wasn’t just Republican politicians. An essential part of the marketing strategy from Fair-and-Balanced Fox News was to convince their viewers that the other networks harbored massive anti-conservative bias. Attacks on the Fourth Estate in the conservative media world have become as common as attacks on the Soviet Union were during the cold war. It’s become a central tenet of the creed.

In short, the efforts by Republicans and the Conservative Media Establishment to discredit the press have worked.

Republicans might respond by saying Republican support for the press has dropped because the press is biased. But to believe that the recent decline is driven primarily by quality would mean that the press became almost four times more biased (against Republicans) in the last 15 years. The far more plausible explanation is that the attacks on the press have been effective.

So, to be clear, I dont think Republican attacks on the press are the only reason for the erosion of trust. Self-inflicted wounds, the rise of fake news, cut-backs in local reporting — they’re all factors, and the press needs to improve its quality in order to regain the public’s trust. But let’s at least be honest about the biggest reason for the recent collapse.

Steven Waldman is founder of LifePosts.com, a platform for online memorials and life milestones. He's a Washington Monthly contributing editor, journalist and author.